Lesson blocks, marking marathons, parents' evenings - schedule math in the language of the timetable.
A teaching day is a chain of fixed-length blocks - lessons, breaks, duties, marking - and planning it means adding durations to clock times over and over. TCalc does exactly that: type the plan as an expression and read off the answer.
It also settles the honest questions: how much of the week do six 45-minute lessons actually take?
A teaching timetable is counted in periods, but a contract is counted in hours, and the two only reconcile if you do the multiplication. Twenty-five periods of fifty minutes is 1,250 minutes - twenty hours fifty minutes - which is a very different number from twenty-five hours, and the gap is precisely the part people forget when they agree to an extra class.
Directed time sits on top of contact time and covers meetings, duties, parents' evenings and cover. Adding the two gives the figure that should be compared against a contractual limit, and keeping them separate is what makes the comparison meaningful.
Twenty-five fifty-minute periods as actual contact hours.
Contact time plus a week of directed time.
A thirty-period timetable on forty-five-minute lessons.
A scheme of work is an effort estimate that has to fit a fixed calendar, and the constraint is teaching weeks rather than calendar weeks. A twelve-week half-term with two lessons a week is twenty-four lessons, less whatever is lost to trips, exams and bank holidays - and the honest figure is the one after those subtractions, not before.
Working backwards from an assessment date is the more common direction. Subtracting today from the exam date gives the days remaining; dividing by the lessons per week gives the number of lessons left, which is the number that actually decides what can be covered.
Lessons available across a twelve-week half-term at two a week.
The same term after three lessons lost to trips and assessment.
Time to a fixed exam date, as a countdown.
Marking is the load most often underestimated, because the per-item time is small and the item count is large. Thirty scripts at eight minutes each is four hours - not an evening, but most of one - and three classes of that in a week is twelve hours on top of contact and directed time.
Doing the multiplication before committing to an assessment schedule is what makes the workload visible while it can still be changed. It also makes the case for staggering assessments concrete rather than anecdotal.
One class set of thirty scripts at eight minutes each.
Three class sets in the same week.
The same marking spread across five evenings.
Six lessons of teaching time.
When does this period end?
Eight parent meetings at 15 minutes each.
Need marking done by noon? That's your start time.
Multiply the lesson length by the count: 45m × 6 = 4h 30m per day, and chain days together for the week. TCalc keeps the minutes exact.
Yes - subtract the duration from the deadline: 12:00 − 90m = 10:30 AM is when you need to start.
Yes - the calculator is free with no sign-up, works in any browser, and there's an Android app. A free account adds cloud-synced history.